The present application relates generally to an improved data processing apparatus and method and more specifically to mechanisms for priming failover capabilities for low latency stateful offload communication adapters.
Modern communication adapters, e.g., network adapters, input/output (I/O) adapters, and the like, provide hardware based stateful offload for low latency communication using protocols such as Remote Direct Memory Access (RDMA). Stateful offload refers to the ability to offload some of the processing typically performed by the host computing system to the communication adapter. For example, the Transmission Control Protocol (TCP) offload engine (TOE) is one example of a stateful offload engine of a communication adapter and is a technology used in network interface cards (NICs) to offload processing of the entire TCP/IP stack to the network controller of the NIC. RDMA is a direct memory access from the memory of one computing device into that of another without involving either computing device's operating system.
When communication adapters that perform stateful offload operations experience an outage in the switch fabric coupling the adapter to the host system, the offloaded state in the adapter is lost to the host system. This makes it difficult to provide high availability solutions with transparent failover for such stateful adapters without application outage.
Known mechanisms attempt to address this issue by utilizing a mechanism referred to as Automatic Path Migration (APM). APM mechanisms operate internal to an adapter and attempt to automatically find an alternative path from the adapter, such as via another physical port of the adapter, to the network when a failure of a communication connection is detected. However, APM mechanisms are limited to finding alternate paths to the switch fabric available via the same adapter or host channel adapter (HCA), i.e. via another physical port of the same adapter/HCA. Thus, the APM mechanisms cannot provide an alternate path when all the ports of an adapter or HCA suffer an outage.